A nitride semiconductor device featuring high saturation electron velocities, wide band gaps and the like may be used as high-voltage and high-output semiconductor devices. Nitride semiconductor devices may include field effect transistors and high electron mobility transistors (HEMTs), for example, an AlGaN/GaN HEMT that includes a GaN electron transit layer and an AlGaN electron supply layer may also be included. AlGaN of the AlGaN/GaN HEMT may bear a distortion caused by a difference in lattice constant between GaN and AlGaN. Highly concentrated two dimensional electron gas (2DEG) may be obtained based on the piezoelectric polarization and spontaneous polarization of AlGaN.
The band gap of GaN may be 3.4 eV which is larger than the band gap of Si (1.1 eV) or the band gap of GaAs (1.4 eV) and GaN may have a high breakdown electric field intensity. Since GaN has a high saturation electron velocity, GaN may be used in semiconductor devices for high-output power supplies operating under high voltage. The nitride semiconductor device may be used in high-efficiency switching elements, high-voltage high-output devices for electric vehicles, etc.
The related technology is disclosed in Japanese Laid-open Patent Publication No. 2000-252299, for example.